凝胶渗透色谱法对碳量子点的纯化及荧光性能研究

Study on the Purification and Fluorescence Properties of Carbon Quantum Dots by Gel Penetrate Chromatography

摘要: 荧光碳量子点是一种尺寸小于10 nm的碳纳米颗粒，具有良好的生物相容性，强水溶性，易于功能化和稳定的光学性能等性质。但是碳点的发光特性与其相对分子质量有关，由于荧光碳量子点非常容易团聚，所以出现激发依赖现象。在碳点制备过程中，不容易得到单分散的荧光碳量子点，所以荧光碳量子点分离纯化是目前存在的最大技术难题之一。本实验以柠檬酸和尿素为原料，采用快速，低成本的熔融法成功制备出了一种具有水溶性好及光稳定性强的荧光碳量子点(CQDs)。并首次对荧光碳量子点采用凝胶色谱柱分离纯化，从而得到了两种不同的碳点馏分。未分离荧光碳量子点具有激发依赖光学性质，而经过分离的荧光碳量子点馏分则具有激发独立的光学性质。对于分离后的馏分，在一定的激发波长范围(340~440 nm)，其发射波长始终为535 nm。说明了该凝胶色谱技术能实现不同相对分子质量的碳点组分的分离。此外，对碳点进行了红外，质谱表征，证明了碳点表面含有大量羟基，羧基，质谱表征结果也表明经过纯化的碳点的相对分子质量范围窄。

Abstract: Carbon quantum dots are particles which are smaller than 10 nm; it has good biocompatibility, strong water solubility, easy to function and stable optical properties. However, the luminescent properties of carbon quantum dots are related to their relative molecular weight. Fluorescent car-bon quantum dots have excitation dependence phenomenon due to easy to be reunite. In the process of preparing carbon quantum dots, it is difficult to obtain single dispersive fluorescent carbon quantum dots, so the separation and purification of fluorescent carbon quantum dots is one of the biggest technical problems existing. In this experiment, fluorescent carbon quantum dots (CQDs) with water solubility and light stability was successfully prepared by using citric acid and urea as raw materials. Two different fractions of carbon quantum dots were obtained by the separation and purification of fluorescent carbon quantum dots by gel column. The unseparated fluorescent carbon quantum dots have excitation dependent optical properties, while the separated fluorescent carbon quantum dots have the optical properties of excitation independence. For the separated fraction, the emission wavelength is always 535 nm at a certain excitation wavelength range (340 - 440 nm). The separation of carbon quantum dots components with different molecular weight can be achieved by gel chromatography. In addition, the infrared and mass spectrum characterization proves that on the surface of the carbon quantum dots containing a large number of hydroxyl, carboxyl, and mass spectrometry characterization results also show that we gained carbon quantum dots with a narrow range of relative molecular mass after the purification of carbon quantum dots.